Failure analysis method of air-conditioning refrigeration system

One look: After watching the air conditioner running

Look at the refrigerant flow in the glass observation window. A uniform and transparent liquid is normal.

Looking at the frost on the low-voltage circuit, the frost on the surface is normal.

Look at the leakage at each joint of the refrigeration system. It is normal to be dry without oil stains.

Look at the working condition of the compressor's magnetic coil. It can be normal to see the water dripping from the evaporator after the compressor is turned on without any abnormal sound. Normally, the air conditioner runs for about 8 minutes, and it is normal for the water to drain from the evaporator water tray.

See if the condenser electronic fan is operating normally.

Second listening: After listening to the air conditioner running

When the compressor is running, there is no noise or impact sound, but it is abnormal.

Listen to whether there is noise in the operation of the evaporator blower, condenser electronic fan, motor, etc., but it is abnormal.

Three touch: After the air conditioner is running

It is normal to touch the high and low pressure pipes of the refrigeration system.

The condenser heat is normal, and there is a temperature difference from the bottom to the top of the condenser, which is normal for the drying filter, and it is normal that there is no obvious temperature difference between the inlet and the outlet.

There should be a significant temperature difference before and after the expansion valve as normal.

It should be normal for the wind from the air outlet in the car to feel cold.

Fourth test: After the air conditioner is running

1. Leak detection with leak detection equipment

Use a leak detector to check for leaks at all joints in the entire system.

2.Check with a multimeter

Check the air-conditioning circuit with a multimeter to determine whether the air-conditioning system circuit has a short circuit or an open circuit fault.

3.Check with a thermometer

A thermometer can be used to determine the failure of the condenser, evaporator, and reservoir.

When the evaporator is working normally, the surface temperature of the evaporator should be as low as possible without frost. When the condenser is working normally, the condenser inlet tube temperature is 70 ° C and the outlet tube temperature is around 50 ° C. The temperature of the accumulator should be about 50 ° C. If the temperature of the accumulator is not consistent, it means that the accumulator is blocked.

4.Check with pressure gauge

Connect the high and low pressure gauges of the manifold pressure gauge to the maintenance valves of the compressor's exhaust and suction ports, respectively. When the air temperature is 30 ℃ ~ 50 ℃ and the engine speed is 2000r / min, check that the wind speed of the fan is adjusted to the high level and the temperature is adjusted to the coldest position. The normal conditions are:

The high-pressure end pressure should be 1.421 ~ 1.470MPa and the low-pressure end pressure should be 0.147 ~ 0.196MPa, otherwise the air-conditioning refrigeration system is faulty.